Resumo

LERMO-SAMANIEGO, Javier; ANTAYHUA-VERA, Yanet  e  CHAVACAN-AVILA, Marcos. Analysis of the seismic activity in the Popocatépetl volcano (Mexico) in 1994-1997. Bol. Soc. Geol. Mex [online]. 2006, vol.58, n.2, pp.253-257. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2006v58n2a8.

In this study, a detailed analysis of the volcano-tectonic earthquakes recorded by the Seismic Network installed in the volcano Popocatepetl during the period 1994-1999 was made. The objective was to determine hypocentral parameters and the nature of the involved seismic source. Results show that earthquakes have magnitudes Md<3.2, depths lower than 12 km and hypocentral location errors lower than 1 km. Epicentral and hypocentral distributions allow to distinguish two groups of earthquakes, each having an specific location: The first one (A-Zone) located under the crater and the second one, SE of the previous one. For the events in the A-zone, the analysis of waveforms and focal mechanisms shows seismic records displaying emergent arrivals and a variety offocal mechanisms, indicating that this seismicity may be related to fracture processes in the volcano walls as a result of magmatic ascension. B-zone earthquakespresent impulsive arrivals and normal mechanisms with a left-lateral component of motion. Thispattern suggest that these events may be associated to normal faulting in a NW-SE direction, coinciding with both the observed direction and focal mechanisms of the fault system "La Pera ", located near the volcano.

Palavras-chave : Volcano Popocatépetl; seismicity; focal mechanisms; Fault System La Pera.